The “Liquid Tree” is Very Cool Actually

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I talk a lot about how we’re living in a dystopia: a pandemic that at-risk people actively choose to ignore, runaway climate change that billionaires actively choose to exacerbate, gun violence that our government actively chooses to tolerate, I could go on and on. But you know what? Today I’m going to take just a few minutes to argue for something that people seem to think is dystopian but is actually very much not: liquid trees.

It seems like every few weeks this bobs up to the top of the social media toilet, with the most recent being a viral tweet reading “big day for people that wanted trees to be replaced by green slime in a glass tank (no one).” Which would be a perfectly fine thing to tweet for some easy retweets had this joke/sentiment not already been expressed approximately 10,000 times before. But this is it, this is my last straw. I’m going to defend the green slime. That’s right, after like two months of nonstop depressing and weird rabbit hole videos, I’m just going to relax and tell you a wholesome tale of human ingenuity.

I get why people see this viral “liquid tree” installation and assume it’s some capitalist invention to replace the humble tree, the first step towards ridding our planet of everything good and natural and replacing it with a cold Bladerunner aesthetic. But that isn’t what it is at all. This is actually a project called Liquid3, created by Dr. Ivan Spasojevi? at the University of Belgrade’s Institute for Multidisciplinary Research for Serbia’s “Climate Smart Urban Development Challenge.” The project won this year’s Index Community award for fostering health and wellbeing.

For starters, Spasojevi? did not create this to “replace” trees. No one is planning to tear through your local urban park, ripping down old growth redwoods and replacing them with glowing slime. This project was inspired by its place of origin: Belgrade, home to two of the top ten dirtiest coal power plants in Europe. In 2020, the Global Alliance for Health and Pollution listed Serbia as the most polluted country in Europe, with an estimated 175 people per 100,000 dying from pollution each year.

You can’t just tree your way out of that! Addressing this issue requires a multi-pronged approach, of government enforcing industry standards, encouraging green spaces, and yeah, coming up with novel solutions that most people wouldn’t immediately think of.

I’m often very critical of people who think they can science-and-technology their way out of large scale issues, especially when they’re reliant on billionaire idiots like Elon Musk to do it. But in this case, it’s academic scientists proposing a solution, they know it’s not an easy cure-all, and the project actually seems to be pretty god damned effective. Oh, also it’s cool. I’m not someone who is interested in the newest iphone or random gadgets, but I can appreciate a well-designed hunk of tech, and this is SUPER COOL.

The “green slime” is actually microalgae. Algae, if you weren’t aware, is responsible for producing about 70% of the oxygen in our atmosphere. It’s really important to our ecosystem, and it’s REALLY good at converting CO2 to O2: this installation takes up the space of two mature trees but is 10 to 50 times more efficient.

It is also installed in a place where trees cannot grow: Belgrade is densely packed, so green space is at a minimum, areas that can be converted to green space are at a minimum, and the pollution makes it difficult for trees to even survive to maturity. 

Are you worried that this installation is using electricity to keep the algae alive? Well you shouldn’t be, because it’s actually providing additional electricity thanks to the solar panels installed on the top, which provide enough power to circulate the algae AND enough leftover to power a nightlight and charge devices you can plug in as you sit and relax on the built-in bench.

Worried about the upkeep of this? Well you shouldn’t be, because the algae thrives in tap water at high and low temperatures, and every six months you remove half of it to use as fertilizer and replace the rest with more tap water and some food.

It’s very much a shame that the kneejerk reaction online has been “dystopia” because Spasojevi? says that “This project aims to popularize and expand the use of microalgae in Serbia, because they can be used in wastewater treatment, as compost for green areas, for the production of biomass and biofuels, as well as for air purification from exhaust gases from the factories”.

The real purpose of this project is to stimulate conversation, to get people thinking about creative ways to tackle big problems like pollution, and to use nature itself to make our world better. Personally I think that’s super fucking cool and I hope that the people of Belgrade, at least, can appreciate the awesome efforts of their scientists.

So that’s all, I just had to get that off my chest. Green slime is cool. Kneejerk cynicism isn’t.

Rebecca Watson

Rebecca is a writer, speaker, YouTube personality, and unrepentant science nerd. In addition to founding and continuing to run Skepchick, she hosts Quiz-o-Tron, a monthly science-themed quiz show and podcast that pits comedians against nerds. There is an asteroid named in her honor. Twitter @rebeccawatson Mastodon Instagram @actuallyrebeccawatson TikTok @actuallyrebeccawatson YouTube @rebeccawatson BlueSky

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